Led tube lamp

ABSTRACT

An LED tube lamp, comprising: a lamp tube; a first circuit board, disposed in the lamp tube, having a plurality of light sources mounted thereon; two lamp caps disposed at respective ends of the lamp tube; a power supply substantially disposed in one or both of the two lamp caps, the power supply having a second circuit board; and a connection structure having a third circuit board, the third circuit board for connecting the first circuit board to the second circuit board thereby connecting the light sources to the power supply.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 16/731,342 filed on 2019 Dec. 31, which claims priority to thefollowing Chinese Patent Applications Nos.: CN 201910001656.8 filed on2019 Jan. 2, CN 201910152736.3 filed on 2019 Feb. 28, CN 201910506394.0filed on 2019 Jun. 12, CN 201910516229.3 filed on 2019 Jun. 14, CN201911179027.0 filed on 2019 Nov. 27, the disclosures of which areincorporated herein in their entirety by reference.

TECHNICAL FIELD

The present disclosure relates to an LED lighting device, and moreparticularly, to an LED tube lamp.

RELATED ART

LED lighting is widely used because its benefits of far less energyconsumption and longevity. The LED fluorescent lamp, commonly known as astraight tube lamp, generally includes a lamp tube, a first circuitboard with a light source disposed in the lamp tube, lamp caps arerespectively disposed at both ends of the lamp tube, and a power supplyis disposed in the lamp caps. The light source and the power supply areelectrical connected through the first circuit board. The light sourceis made from a plurality of LEDs arranged on the first circuit board,and the plurality of LEDs are sequentially arranged along the length ofthe lamp tube.

The traditional LED tube lamp includes a second circuit board(electronic components are installed on the second circuit board to forma power supply), a first circuit board and a lamp cap. The secondcircuit board far from the end of its matched lamp cap connects with thefirst circuit board.

Assuming that the first circuit board is a flexible circuit board, andthe connection between the second circuit board (power circuit board)and the first circuit board (flexible circuit board) needs to becompleted outside the lamp tube (the diameter of the lamp is relativelysmall that it is difficult to achieve the connection between the powercircuit board and the flexible circuit board in the lamp tube), when theconnection is completed, the power circuit board is inserted into thelamp tube. There are disadvantages of this method:

1. After the connection between the power circuit board and the flexiblecircuit board is completed outside the lamp tube, the power circuitboard needs to be inserted into the lamp tube, and the process ofinserting the power circuit board into the lamp is rather difficult,especially product T5 because the diameter of product T5 is smaller, itis more difficult to insert into the power circuit board.

2. The end of the flexible circuit board needs to be provided with afree portion. Therefore, during the insertion of the power circuit boardinto the lamp tube, the free portion can be driven into the lamp tube.The length of the free portion needs to be at least longer than that ofthe power circuit board from outside the lamp tube. If the length of thefree portion is too long, the stability of the connection will belowered. After the power circuit board is inserted into the lamp tube,the arrangement of the free portion in the lamp tube cannot becontrolled, and the light source may be blocked, such uncertainties mayappear.

3. After the connection between the power circuit board and the flexiblecircuit board is completed, during the process of inserting the powercircuit board into the lamp tube, the flexible circuit board may bestripped from the power circuit board due to dragging, resulting inconnection failure.

4. When the power circuit board is in direct contact with the flexiblecircuit board, and there is a risk of fire.

5. The thermal conductivity of the flexible circuit board is relativelypoor. The heat generated during the operation of the light source maynot be dissipated in time. Under long-term high-temperature environment,it is easy to damage the light source or the electronic components ofthe power supply.

6. The supportability of the flexible circuit board is relatively poor.After the light source is set on the flexible circuit board, the problemthat each LED lamp bead is not on the same plane is prone to cause somelight emission problems.

In summary, in view of the shortcomings and defects of the existing LEDtube lamp, how to design an LED tube lamp is a technical problem thatneeds to be solved by those skilled in the art.

SUMMARY

The present disclosure is directed to a new LED tube lamp and featuresin various aspects to solve the above problems.

The present disclosure provides an LED tube lamp comprising a lamp tube;a first circuit board, disposed in the lamp tube, having a plurality oflight sources mounted thereon; two lamp caps disposed at respective endsof the lamp tube; a power supply substantially disposed in one or bothof the two lamp caps, the power supply having a second circuit board;and a connection structure having a third circuit board, the thirdcircuit board for connecting the first circuit board to the secondcircuit board thereby connecting the light sources to the power supply.

In some embodiments, the thermal conductivity of the first circuit boardis higher than that of the third circuit board.

In some embodiments, the thermal conductivity of the third circuit boardis higher than that of the second circuit board.

In some embodiments, the power supply includes an electronic component,the electronic component of the power supply includes one or moreheating elements, at least one of the heating elements of the electroniccomponent thermally contacts to the third circuit board.

In some embodiments, the power supply includes an electronic component,the electronic component of the power supply includes a heating element,the heating element for dissipating heat in the form of heat radiationto the third circuit board.

In some embodiments, the hardness of the first circuit board is greaterthan that of the third circuit board.

In some embodiments, the hardness of the second circuit board is greaterthan that of the third circuit board, the power supply and the thirdcircuit board are stacked, and the third circuit board is bent anddeformed to adapt to the power supply.

In some embodiments, the first circuit board is fastened on the innersurface of the lamp tube while the third circuit board is not fastenedon the inner surface of the lamp tube, the third circuit board is a softcircuit board or a flexible circuit board.

In other embodiments, the second circuit board has a first end and asecond end in a axial direction of the lamp tube, and the first end ofthe second circuit board is closer to the matching lamp cap, the firstend of the second circuit board is connected to one end of the thirdcircuit board while the other end of the third circuit board isconnected to the first circuit board.

In some embodiments, the second circuit board is directly soldered tothe third circuit board.

In some embodiments, the first circuit board has a first pad, and thethird circuit board has a second pad, the first circuit board and thethird circuit board are directly soldered through the first pad and thesecond pad.

In some embodiments, the first pad of the first circuit board is spacedfrom the end of the first circuit board in a longitudinal direction toform a connection section, one end of the third circuit board is placedon the connection section and the second pad of the third circuit boardcorresponds to the first pad of the first circuit board in the lengthdirection of the lamp tube.

In some embodiments, the connection section is a part of the firstcircuit board, and the hardness of the connection section is higher thanthat of the third circuit board.

In some embodiments, the power supply includes an electronic component,the first pad of the first circuit board is disposed on a side of thefirst circuit board with the light sources, and the second pad of thethird circuit board is disposed on a side of the third circuit boardrelatively close to a side of the electronic component.

In some embodiments, the second circuit board and the third circuitboard are separated by the electronic component.

In some embodiments, the electronic components include capacitor,transformer or inductor.

In some embodiments, the second circuit board and the third circuitboard are disposed at opposite sides in the width direction of the lamptube.

In some embodiments, the thickness of the third circuit board is smallerthan that of the second circuit board.

In some embodiments, a hollow conductive pin is arranged on the lampcap, the LED tube lamp includes a connecting wire, and the hollowconductive pin is fastened on the lamp cap, one end of the connectingwire is electrically connected to the hollow conductive pin, the otherend of the connecting wire is connected to the second circuit board, theconnecting wire includes a fusible portion and the fusible portion is alow-melting alloy.

In some embodiments, the melting point of the fusible portion is lessthan or equal to the melting point of any conductive substance on thesecond circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a three-dimensional exploded diagram of an LED tubelamp according to an embodiment of the instant disclosure;

FIG. 2 illustrates a perspective diagram of a lamp cap according to anembodiment of the instant disclosure;

FIG. 3 illustrates a schematic diagram showing the lamp cap connected tothe second circuit board in FIG. 2;

FIG. 4 illustrates a three-dimensional schematic diagram showing thelamp cap structure in FIG. 2;

FIG. 5 illustrates a perspective diagram of a lamp cap according to anembodiment of the instant disclosure;

FIG. 6 illustrates a schematic diagram showing the lamp cap connected tothe second circuit board in FIG. 5;

FIG. 7 illustrates a three-dimensional schematic diagram showing thelamp cap structure in FIG. 3;

FIG. 8 illustrates a perspective diagram of showing the lamp capconnected to the second circuit board;

FIG. 9 illustrates a three-dimensional schematic diagram showing thelamp cap structure in FIG. 8;

FIG. 10 illustrates a perspective diagram of showing the lamp capaccording to an embodiment of the instant disclosure;

FIG. 11 illustrates a schematic diagram showing the lamp cap connectedto the second circuit board in FIG. 10;

FIG. 12 illustrates a three-dimensional schematic diagram showing thelamp cap structure in FIG. 10;

FIG. 13 illustrates a perspective diagram of showing the lamp capstructure according to other embodiments of the instant disclosure;

FIG. 14 illustrates a perspective diagram of showing the lamp capstructure according to an embodiment of the instant disclosure;

FIG. 15 illustrates a partially steric cross section of the lamp capstructure according to an embodiment of the instant disclosure;

FIG. 16 illustrates a three-dimensional schematic diagram showing thelamp cap structure;

FIG. 17 illustrates a three-dimensional schematic diagram showing thesecond circuit board structure;

FIG. 18 illustrates a cross section diagram of the lamp cap structure;

FIG. 19 illustrates a three-dimensional schematic diagram showing thesecond circuit board structure;

FIG. 20 illustrates a partial diagram showing the connection structureof the power supply and the first circuit board according to anembodiment of the instant disclosure;

FIG. 21 illustrates a zoom-in diagram showing the structure B in FIG.20;

FIG. 22 illustrates a partial schematic diagram showing the connectionstructure of the second circuit board and the first circuit boardaccording to other embodiments of the instant disclosure;

FIG. 23 illustrates a cross section diagram of partial perspectivediagram of the LED tube lamp according to an embodiment of the instantdisclosure;

FIG. 24 illustrates a perspective diagram showing circuit board 1according to an embodiment of the instant disclosure;

FIG. 25 illustrates a perspective diagram showing circuit board 2according to an embodiment of the instant disclosure;

FIG. 26 illustrates a cross section diagram showing the connection ofthe wire and the second circuit board;

FIG. 27 illustrates a cross section diagram showing state I of thefusing part folded;

FIG. 28 illustrates a cross section diagram showing state II of thefusing part folded;

and

FIG. 29 illustrates a cross section diagram of partial perspectivediagram of the LED tube lamp according to an embodiment of the instantdisclosure.

DETAILED DESCRIPTION

In order to better understanding of the present disclosure, the presentdisclosure will be described more fully with reference to theaccompanying drawings. The drawings show a preferred embodiment of thedisclosure. However, the present disclosure is implemented in manydifferent forms and is not limited to the embodiments described below.Rather, these embodiments provide a thorough understanding of thepresent disclosure. The following directions such as “axial direction”,“upper”, “lower” and the like are for more clearly indicating thestructural position relationship, and are not a limitation on thepresent invention. In the present invention, the “vertical”,“horizontal”, and “parallel” are defined as: including the case of ±10%based on the standard definition. For example, vertical usually refersto an angle of 90 degrees with respect to the reference line, but in thepresent invention, vertical refers to a condition including 80 degreesto 100 degrees.

Please refer to FIG. 1, the instant disclosure provides an embodiment ofthe LED tube lamp which comprises a lamp tube 1, a first circuit board 2disposed in the lamp tube 1 and two lamp caps 3 respectively disposed atboth ends of the lamp tube 1, and a hollow conductive pins 4 forconnecting an external power supply is disposed on the two lamp caps 3.The lamp tube 1 is a plastic lamp tube, a glass lamp tube, or a plasticand metal mixed lamp tube, or a glass and metal mixed lamp tube. Thesize of the two lamp caps 3 (the axial length dimension of the lamp cap3) is the same or different. The instant disclosure provides anembodiment of multiple light sources 21 set on the first circuit board2. When the light source 21 is in operation, the light source 21 forms aheat conduction path with the lamp tube 1 and the first circuit board 2.In this way, it is convenient to quickly dissipate the heat generatedfrom the inside of the lamp tube 1 to the outside of the lamp tube 1during the operation of the light source 21. The instant disclosureprovides an embodiment of the first circuit board 2 being fixed to theinner surface of the lamp tube 1 by an adhesive, that is, the firstcircuit board 2 is fixed to the inner surface of the lamp tube 1 by anadhesive. The first circuit board 2 forms a heat conduction path withthe lamp tube 1 through glue. In some embodiments, the first circuitboard 2 is fixed to the inner surface of the lamp tube 1 with athermally conductive adhesive to improve the thermal conductivity. Apower supply 5 is disposed in the lamp caps 3, and the power supply 5and the light source 21 are electrically connected by the first circuitboard 2. At least a part of the power supply 5 in a radial projection ofthe LED tube lamp overlaps the lamp caps 3. The power supply 5 can be asingle unit (for example, the power supply modules are all concentratedin one component and disposed in one of the lamp caps 3(non-light-emitting area)). Alternatively, the power supply 5 is alsodivided into two parts, which are called dual bodies (that is, all powersupply modules are respectively installed in two parts), and the twoparts are respectively installed in the lamp caps 3 (non-light-emittingareas) at both ends of the lamp tube 1. In this embodiment, the powersupply 5 includes a second circuit board 51 (as shown in FIG. 3) and aplurality of electronic components 52.

Please refer to FIG. 2 to FIG. 4, the instant disclosure provides anembodiment of a lamp cap 3 which can be applied to an LED tube lamp. Thelamp cap 3 includes a side wall 31 and an end wall 32. The side wall 31is tubular. The side wall 31 and the lamp tube 1 are coaxially set andconnected to each other. The meaning of coaxial is that the lamp cap 3and the lamp tube 1 may have tolerances during manufacture, so the axesof the lamp cap 3 and the lamp tube 1 may be slightly offset, butgenerally the lamp cap 3 and the lamp tube 1 are coaxial. The plane ofthe end wall 32 is vertical or substantially vertical to the axialdirection of the side wall 31, and the end wall 32 connects to the endof the side wall 31 away from the lamp tube 1. The meaning of verticalis that the end wall 32 and the side wall 31 may have tolerances duringmanufacture, so the end wall 32 and the side wall 31 are not 90 degreesvertical but slightly inclined, and this still belongs to the verticalrange. However, even if the end wall 32 is slightly inclined withrespect to the axial direction of the side wall 31, the end wall 32 andthe side wall 31 may form a space for installing the power supply 5 andmay match the lamp holder. The side wall 31 and the end wall 32 form aninternal space of the lamp cap 3, and the power supply 5 is at leastpartially installed in the internal space of the lamp cap 3.

As shown in FIG. 2, the lamp cap 3 includes a first rib 33. The firstrib 33 is set on the inner surface of the side wall 31 of the lamp cap3, and the first rib 33 extends in the axial direction of the lamp cap3. The first rib 33 may be continuously integrated in the axialdirection of the lamp cap 3 or may be multi-segmented. The first rib 33and the inner surface of the side wall 31 form a slot 35, and the secondcircuit board 51 is inserted into the slot 35 and fixed. In specific,please refer to FIG. 3, the second circuit board 51 has a first surface511 and a second surface 512 which are opposite and parallel to eachother, and the first surface 511 and the second surface 512 aresubstantially parallel to the axial direction of the lamp cap 3. Whenthe second circuit board 51 is inserted into the slot 35 and fixed, thefirst surface 511 of the second circuit board 51 corresponds to thesurface on the side of the first rib 33, and the second surface 512 ofthe second circuit board 51 corresponds to the inner surface of the sidewall 31, so the second circuit board 51 is fixed. Preferably, the firstsurface 511 of the second circuit board 51 abuts on the first rib 33,and the edge of the second surface 512 of the second circuit board 51abuts on the inner surface of the side wall 31 so that the circuit board51 is fastened. In actual use, the first rib 33 are used in pairs, thatis, the slot 35 is formed on the two sides of the lamp cap 3 to fastenthe two sides of the second circuit board 51. As shown in FIG. 2, theslot 35 are arranged in four groups, that is, two pairs of the slots 35,and the two pairs of slots 35 are arranged symmetrically to each other.Therefore, when the lamp cap 3 is connected to the second circuit board51, the second circuit board 51 can be selectively inserted into the twopairs of the slots 4 according to the actual position.

In this embodiment, the first rib 33 may be made of an elastic material(such as plastic). In this way, the first rib 33 may provide certaindeformed space to adapt an error of the thickness or different sizes ofthe thickness of the second circuit board 51 during manufacture.

Please refer to FIGS. 2 to 4, a hole 3001 is set on the lamp cap 3. Withthe setting of the hole 3001, on the one hand, the heat generated by thepower module inside the lamp cap 3 is dissipated without causing theinside of the lamp cap 3 to be in a high temperature state. On the otherhand, if the humidity is too high, water vapor is formed on the innerwall of the lamp tube 1, which reduces the reliability of the internalcomponents of the lamp cap 3. In another embodiment of the instantdisclosure, the holes 3001 are symmetrically arranged with respect tothe hollow conductive pinholes of the lamp cap 3, so that no matter thesecond circuit board 51 is installed in any group of the slots 4, thereare corresponding holes 3001 dissipating heat.

As shown in FIG. 5, FIG. 6 and FIG. 7, a lamp cap 3 proposed of theinstant disclosure can be applied to an LED tube lamp. The differencebetween the lamp cap 3 proposed in this embodiment and the lamp cap 3(the lamp cap 3 shown in FIGS. 2 to 4) of the previous embodiment isthat the first rib 33 of the lamp cap 3 is provided with an couplingstructure 331, and the coupling structure 331 is protruded set on thefirst rib 33 with respect to one side surface of the first surface 511of the second circuit board 51. The coupling structure 331 extends alongthe axial direction of the lamp cap 3, and the coupling structure 331may be continuously integrated in the axial direction of the lamp cap 3,or may be a multi-segment type. The coupling structure 331 has acoupling surface 3311, and the coupling surface 3311 corresponds to thefirst surface 511 of the second circuit board 51. For example, the firstsurface 511 of the second circuit board 51 and the coupling surface 3311abut. When the second circuit board 51 is fastened, the first surface511 of the second circuit board 51 corresponds to the coupling surface3311, and the second surface 512 thereof corresponds to the innersurface of the side wall 31, that is, the coupling surface 3311 and theinner surface of the side wall 31 forms a slot 35. Preferably, the firstsurface 511 of the second circuit board 51 abuts the coupling surface3311, and the edge of the second surface 512 of the second circuit board51 abuts the inner surface of the side wall 31, so that the secondcircuit board 51 is fixed. Compared with the first surface 511 of thesecond circuit board 51 directly corresponding to the surface on theside of the first rib 33 (the first surface 511 directly contacts thesurface on the side of the first rib 33), the coupling portion 331 cannarrow the contact area of the first surface 511 of the second circuitboard 51 and when the first rib 33 is small, the contact area isnarrowed during the process of inserting the second circuit board 51into the lamp cap 3, which can reduce the resistance during insertion.

As shown in FIG. 7, the coupling structure 331 is provided with a firstguide unit 3312 at an end of the lamp cap 3 axially away from the endwall 32. When the first guide unit 3312 is away from the end wall 32, itis opposite to the first rib 33 where the height of the surfacegradually decreases. This facilitates the insertion of the secondcircuit board 51.

As shown in FIG. 5, the coupling structure 331 is vertical orsubstantially vertical to the first rib 33. When the coupling structure331 is far from the surface of the first rib 33, the width dimension ofthe cross-section thereof gradually shortened. That is, the positionwhich the coupling structure 331 is connected to the first rib 33 hasthe largest width. In this way, the strength of the connection betweenthe coupling structure 331 and the first rib 33 can be increased, andbreakage of the coupling structure 331 at the connection portion withthe first rib 33 can be prevented during use. In some embodiments, inorder to prevent the connection between the coupling structure 331 andthe first rib 33 from being broken, a stress relief method may beadopted. For example, the connection portion between the couplingstructure 331 and the first rib 33 is set as a circular arc transitionconnection (not shown in the drawing).

As shown in FIG. 13, in some embodiments, in order to narrow the contactarea between the first rib 33 and the second circuit board 51, thefollowing settings can be made. The second circuit board 51 is parallelto the axial direction of the lamp cap 3, and an angle is formed betweenthe first rib 33 and the second circuit board 51, so that the end of thefirst rib 33 contacts the first surface 511 of the second circuit board51 to narrow the contact area between the first rib 33 and the secondcircuit board 51 and reduce the resistance of the insertion of thesecond circuit board 51 into the slot 35. In this embodiment, an angle cbetween the first rib 33 and the second circuit board 51 is an acuteangle. The contact between the first rib 33 and the second circuit board51 is a line contact.

As shown in FIG. 8 and FIG. 9, in this embodiment, a lamp cap 3 can beapplied to an LED tube lamp. The difference between the lamp cap 3 ofthis embodiment and the lamp cap 3 (the lamp cap 3 shown in FIGS. 5 to7) of the foregoing embodiment is that the lamp cap 3 further includes apositioning unit 36 provided on the inner surface of the side wall 31,It is extended along the axial direction of the lamp cap 3. Thepositioning unit 36 corresponds to the side surface of the secondcircuit board 51 to limit the side surface of the second circuit board51 and prevent the second circuit board 51 from being deflected from theaxial direction of the lamp cap 3, thereby causing the second circuitboard 51 skewed and cannot be inserted when the card slot 35 isinserted.

As shown in FIG. 8, the positioning unit 36 maintains a gap with theside of the second circuit board 51 to prevent the positioning unit 36from generating a certain resistance when the second circuit board 51 isinserted into the slot 35. The positioning unit 36 is continuouslyintegrated in the axial direction of the lamp cap 3.

As shown in FIG. 8, the position of the positioning unit 36 does notexceed the position of the coupling surface 3311 in the width of thelamp cap 3. In order to prevent the set-up of the positioning unit 36from affecting the depth of the slot 35 in the width of the lamp cap 3.

As shown in FIG. 9, a second guide unit 361 features the positioningunit 36 away from the end wall 32 at an end of the lamp cap 3 in theaxial direction. As the second guide unit 361 moves away from the endwall 32, the height of the opposing second guide unit 361 of the innersurface of the side wall 31 gradually descended. This facilitates theinsertion of the second circuit board 51.

As shown in FIG. 10, FIG. 11, and FIG. 12, in this embodiment, a lampcap 3 can be applied to an LED tube lamp. The difference between thelamp cap 3 of this embodiment and the lamp cap 3 (the lamp cap 3 shownin FIGS. 8 to 9) of the foregoing embodiments is that the lamp cap 3further includes a second rib 34. A slot 35 is formed between the firstrib 33 (the coupling structure 331 of the first rib 33) and the secondrib 34, and the second rib 34 is protruded from the inner surface of theside wall 31. That is, the first surface 511 of the second circuit board51 corresponds to the first rib 33 (the coupling structure 331 of thefirst rib 33), and the second surface 512 of the second circuit board 51corresponds to the second rib 34. The side surface of the second circuitboard 51 corresponds to the positioning unit 36. As shown in FIG. 10,the second rib 34 is vertical to the first rib 33, and an end portion ofthe second rib 34 corresponds to the coupling structure 331 of the firstrib 33. By making the second rib 34 vertical to the first rib 33 andusing the lower end portion of the second rib 34 to correspond to thecoupling structure 331, in use, only the end portion of the second rib34 contacts the second circuit board 51, which can narrow the contactarea between the second rib 34 and the second circuit board 51 is toreduce the resistance when the second circuit board 51 is inserted.

As shown in FIGS. 10 and 11, the ratio of the width a of the slot 35 tothe thickness b of the second circuit board 51 is 1:0.9 to 1:1.25. Sincethe first rib 33 is made of an elastic material, the slot 35 iscompatible with a certain range of the thickness of the second circuitboard 51 which has a wider applicable field. Preferably, the ratio ofthe width a of the slot 35 to the thickness b of the second circuitboard 51 is 1:1 to 1:1.2, so the second circuit board 51 does not loosenafter being inserted into the slot 35.

As shown in FIG. 11 and FIG. 12, the second rib 34 extends in the axialdirection of the lamp cap 3. A third guide portion 341 is set at the endof the second rib 34 away from the end wall 32 in the axial direction ofthe lamp cap 3. When the third guide portion 341 moves away from the endwall 32, the height of the third guide portion 341 gradually descends.This facilitates the insertion of the second circuit board 51.

The ratio of the thickness of the first rib 33 to the thickness of theside wall 31 (to the thickness of the side wall 31 partially in contactwith the first rib 33) is between 1:0.8 and 1:2.5. That is, thethickness of the first rib 33 and the thickness of the side wall 31 arerelatively uniform. The first rib 33 and the lamp cap 3 by resin areintegrally molded. When the first rib 33 is formed on the inner surfaceof the side wall 31 at certain thickness (in the case where the wallthickness is relatively uniform), the outer surface of the side wall 31is formed less likely to leave marks. If the thickness of the first rib33 is too thick (beyond the above ratio), on one hand, it will affectthe elasticity of the first rib 33, and further affect the insertion ofthe second circuit board 51; on the other hand, due to the flow abilityand internal stress of the resin when the outer surface of the side wall31 is formed, a mark (a shrinkage mark) is formed on the outer surfaceof the side wall 31, and the lamp cap 3 is defective.

As shown in FIG. 7, FIG. 9 and FIG. 12, the first guide portion 3312,the second guide portion 361, and the third guide portion 341 are allset relatively to the direction of the slot 35 so that they can operatein the second circuit board 51.

As shown in FIG. 10, FIG. 11 and FIG. 12, a proximal end 37 is set atthe other end of the lamp cap3 axially opposite to the end wall 32. Thedistance between the proximal end 37 and the end of the first rib 33close to the proximal end 37 in the axial direction and the proximal end37 and the end of the second rib 34 close to the proximal end 37 in theaxial direction is different. Preferably, the distance between theproximal end 37 and the end of the first rib 33 close to the proximalend 37 in the axial direction is shorter than the distance between theproximal end 37 and the end of the second rib 33 close to the proximalend 37 in the axial direction. That is, the second circuit board 51first corresponds to the first rib 33 during the insertion process, andthe first rib 33 supports or guides the second circuit board 51, andthen corresponds to the second rib 34 (the second circuit board 51 isinserted into the slot 35), thereby facilitating the insertion of thesecond circuit board 51. If the distance between the proximal end 37 andthe end of the first rib 33 close to the proximal end 37 in the axialdirection is equal to the distance between the proximal end 37 and theend of the second rib 34 close to the proximal end 37 in the axialdirection. It is necessary for the second circuit board 51 at thebeginning needs to align with the entrance of the slot 35, whichincreases the difficulty of the insertion of the second circuit board51.

As shown in FIG. 14, in this embodiment, a lamp cap 3 can be applied toan LED tube lamp. The difference between the lamp cap 3 of thisembodiment and the lamp cap 3 (the lamp cap 3 shown in FIGS. 10 to 12)of the previous embodiments is that the second rib 34 is convexly set onthe inner surface of the side wall 31, and the second rib 34 is parallelor substantially parallel to the first rib 33. The first rib 33 and thesecond rib 34 form a slot 35, and the second circuit board 51 is snappedinto the slot 35 for fastening. In order to narrow the contact areabetween the slot 35 and the second circuit board 51, a couplingstructure 331 is set on at least one of the first rib 33 and the secondrib 34. Preferably, a coupling structure 331 is set on the first rib 33and the second rib 34 each.

In the above embodiments, when the second circuit board 51 is installedin the end cap 3, the second circuit board 51 and the shaft center ofthe lamp cap 3 maintain a distance. Therefore, the first surface 511 ofthe second circuit board 51 corresponds to more space in the lamp cap 3,and the second surface 512 of the second circuit board 51 corresponds toa relatively small space in the lamp cap 3. Therefore, the electroniccomponents of the power supply 5 are being set, the first surface 511 isset on larger electronic components, such as capacitors, transformers,inductors, etc., and the second surface 512 is set on smaller electroniccomponents, such as chip resistors, chip capacitor, IC (controlcircuit).

Referring to FIG. 15 and FIG. 16, in this embodiment, a lamp cap 3 canbe applied to an LED tube lamp. The lamp cap 3 includes a body 301 andan insulating portion 302. The insulating portion 302 constitutes atleast a part of an end portion of the lamp cap 3, and a hollowconductive pin 4 is disposed on the insulating portion 302. Theinsulating portion 302 has an inner side surface 3021, and a slot 3022is set on the inner side surface 3021. The longitudinal width of theslot 3022 matches with the second circuit board 51 so that the secondcircuit board 51 can be inserted into the slot 3022 for fastening. Thisachieves the function of fastening the power supply 5 in the lamp cap 3.In specific, the slot 3022 restricts the power supply 5 from moving inthe up and down direction on the surface of the second circuit board 51.The material of the body 301 in this embodiment is aluminum or analuminum alloy, and the insulating portion 302 is made of an insulatingmaterial, such as plastic, ceramic, or the like. In this embodiment, twosets of the slots 3022 are installed, and the two sets of the slots 3022are symmetrically installed on the insulating portion 302. The secondcircuit board 51 can be inserted into one of the two sets of the slots3022 according to actual assembly conditions. Specifically, the two setsof the slots 3022 are symmetrically installed with respect to a planepassing through the axis of the lamp tube 1 and parallel to the plane ofthe second circuit board 51.

Please refer to FIG. 15, FIG. 16 and FIG. 17, in this embodiment, theinsulating portion 302 includes a bottom wall 3023, a first side wall3024, and a second side wall 3025, and the bottom wall 3023, the firstside wall 3024, and the second side wall 3025 form the slot 3022 and theend of the bottom wall 3023 form the bottom of the slot 3022. The end ofthe bottom wall 3023 and the inner side surface 3021 maintain space.Therefore, after the second circuit board 51 of the power supply 5 isinserted into the slot 3022, the second circuit board 51 can maintainspace from the inner side surface 3021 to provide air flowing passagefor space convection above and below the second circuit board 51.

Please refer to FIG. 16 and FIG. 17, in this embodiment, the first sidewall 3024 has a first coupling surface 30241, the second side wall 3025has a second coupling surface 30251, the first coupling surface 30241,and the second coupling surface 30251 collectively constitutes sidewalls on both sides of the slot 3022. In this embodiment, the width orarea of the first coupling surface 30241 is configured to be larger thanthe width or area of the second coupling surface 30251 (the width refersto the dimension along the width direction of the lamp tube 1). Duringthe insertion of the second circuit board 51 into the slot 3022, thesecond coupling surface 30251 provides a small frictional force when itcomes into contact with the second circuit board 51 due to the smallwidth or area; and the second circuit board 51 after the slot 3022 isinserted, the first coupling surface 30241 provides better support forthe second circuit board 51 due to the larger width or area, so as toimprove the stability of the power supply 5 for fastening.

Please refer to FIG. 16 and FIG. 17, in this embodiment, the first sidewall 3024 has a first guide surface 30242 while the second side wall3025 has a second guide surface 30252. The first guide surface 30242 andthe second guide surface 30252 together form an opening of the slot 3022to facilitate the second circuit board 51 inserted into the slot 3022through the opening.

Please refer to FIG. 16 and FIG. 17, in this embodiment, a limitingportion 5011 is set on an end portion of the second circuit board 51,and the bottom wall 3023 of the limiting portion 5011 is matched torestrict the movement from the second circuit board 51 in the widthdirection.

In specific, the limiting portion 5011 includes a notch 5111, and thebottom wall 3023 is stuck in the notch 5111, so as to restrict themovement from the second circuit board 51 in the width direction. Thenotch 5111 in this embodiment has a circular arc shape.

In this embodiment, the ratio of the depth of the slot 3022 to thelength of the second circuit board 51 is at least 0.08 or more toimprove the stability of fastening the second circuit board 51 to theslot 3022. Preferably, the ratio of the depth of the slot 3022 to thelength of the second circuit board 51 is at least 0.1 or more. Morepreferably, the ratio of the depth of the slot 3022 to the length of thesecond circuit board 51 is at least 0.12 or more. The specific size ofthe depth of the slot 3022 in this embodiment is 2 to 5 mm.

In this embodiment, the ratio of the width of the slot 3022 to thethickness of the second circuit board 51 is 0.9:1 to 1.2:1 to achieve aproper degree of tightness. On one hand, the ratio is to prevent thecircuit layer of the second circuit board 51 damaged by the card slot3022 when the second circuit board 51 is inserted into the slot 3022. Onthe other hand, the ratio is to prevent the excessive space resulting inshaking of the power supply 5 when the second circuit board 51 isinserted into the slot 3022. Preferably, the ratio of the width of theslot 3022 to the thickness of the second circuit board 51 is 0.95:1 to1.1:1. More preferably, the ratio of the width of the slot 3022 to thethickness of the second circuit board 51 is 0.95:1 to 1:1.

Please refer to FIG. 18, in this embodiment, in order to raise thewithstand voltage value of the lamp cap 3, a certain straight-lineddistance is maintained between the hollow conductive pin 4 and the body301 of the lamp cap 3 through the arrangement of the insulating portion302. Preferably, the cumulative creepage distance between the hollowconductive pin 4 and the body 301 of the lamp cap 3 is at least 4 mm intotal. More preferably, the cumulative creepage distance between thehollow conductive pin 4 and the body 301 of the lamp cap 3 is at least4.5 mm. Preferably, the cumulative creepage distance between the hollowconductive pin 4 and the body 301 of the lamp cap 3 is at least 5 mm. Asshown in FIG. 18, the creepage distance between the hollow conductivepin 4 and the body 301 of the lamp cap 3 is divided into four sectionsof lengths a, b, c, and d, which satisfies: a+b+c+d≥4 mm.

In this embodiment, in order to accommodate the end of the hollowconductive pin 4 in the width direction, the dimension of a is 0.5 mm to1 mm to facilitate the installing and fastening of the hollow conductivepin 4 (the end portion of the hollow conductive pin 4 is protruding inthe radial direction compared to the body of the hollow conductive pin4).

In this embodiment, in order to accommodate the end of the hollowconductive pin 4 in the length direction, the dimension of b is 0.35 mmto 0.5 mm.

In this embodiment, the dimension of c is 1.8 mm to 3 mm to ensure themechanical strength of the insulating portion 302.

Please refer to FIG. 18 and FIG. 19, in this embodiment, a convexportion 3026 is set on the outer edge of the insulation portion 302, anda hole 311 at the end of the body 301 substantially matches the outercontour of the insulation portion 302. By pressing the body 301 forms agroove 3012, so that the convex portion 3026 is disposed in the groove3012, and the insulating portion 302 is fastened.

In this embodiment, the shortest distance between the second circuitboard 51 and the inner wall of the body 301 in the width direction ofthe lamp tube 1 is greater than 3 mm to ensure that the second circuitboard 51 has a sufficient space from the body 301. Compared with theexisting metal lamp cap, the existing metal lamp cap fails toeffectively fasten the second circuit board 51 of the power supply 5.Therefore, the distance between the inner wall of the body 301 of theexisting metal lamp cap and the second circuit board 51 cannot befastened, which may easily result in the second circuit board 51contacting the body of the metal lamp cap, leaving a hidden safetyissue.

Please refer to FIG. 15, the lamp tube 1 in this embodiment includes abody region 102 and end region 101 respectively disposed at two ends ofthe body region 102. The body 21 of the lamp cap 3 is sleeved on the endregion 101. The outer diameter of the tip region 101 is smaller than theouter diameter of the body region 102. The lamp cap 3 is sleeved on theend region 101, and the difference between the outer diameter of thelamp cap 3 and the outer diameter of the lamp body region 102 becomessmaller or completely flat, or the outer diameter of the lamp cap 3 issmaller than the outer diameter of the lamp body region 102. The benefitof this arrangement is that during transportation, the package supportdoes not easily contact the lamp cap 3, so that the lamp cap 3 does notbecome the only stress point, and the portion where the lamp cap 3 isconnected to end region 101 of the lamp tube 1 is broken due to stressconcentration which improves the quality and aesthetics of the product.

In this embodiment, the first circuit board 2 is a soft circuit board ora flexible circuit board, and most areas of the first circuit board 2(for example, more than 90% of the areas) are fastened to the innersurface of the lamp tube 1 and are not fastened to a portion of theinner surface of the lamp tube 1 to form a free portion 2001, and thefree portion 2001 and the second circuit board 51 are fastened bywelding. During assembly, the soldered end of the free part 2001 and thesecond circuit board 51 will drive the free part 51 to shrink into theinterior of the lamp tube 1 and finally form an “S” or “Z” shape (viewedfrom the side of the lamp tube 1).

In this embodiment, the second circuit board 51 has a first surface anda second surface, wherein an electronic component 52 is installed on thefirst surface, and the electronic component 52 includes a capacitor, anelectrolytic capacitor, a fuse, or a transformer. The distance betweenthe portion of the first circuit board 2 attached to the inner surfaceof the lamp tube 1 and the second surface of the second circuit board 51in the width direction of the lamp tube 1 is greater than 3.5 mm. Toensure that there is enough space between the two to accommodate thefree portion 2001, to prevent the pins of the electronic component 52 onthe second circuit board 51 from damaging the free portion 2001 of thefirst circuit board 2. In addition, the distance between the portion ofthe first circuit board 2 attached to the inner surface of the lamp tube1 and the second surface of the second circuit board 51 in the widthdirection of the lamp tube 1 is less than half the diameter of the innersurface of the lamp tube 1 in order to ensure that there is sufficientspace between the first surface of the second circuit board 51 and theinner surface of the lamp tube 1 to accommodate the electronic component2.

In this embodiment, the LED tube lamp is model T8 and the outer diameterof the lamp tube 1 is around 25.4 mm.

Please refer to FIG. 20, in some embodiments, the present disclosureprovides a connection structure between a power supply 5 and a firstcircuit board 2, which can be applied to an LED tube lamp, wherein thefirst circuit board 2 and the second circuit board 51 are connectedthrough a connection portion. The connection portion can be a wire, amale and a female plug, and a pin. The connection portion in thisembodiment adopts a third circuit board 7, that is, the first circuitboard 2 and the second circuit board 51 are connected through the thirdcircuit board 7, so that the light source 21 and the power supply 5 areelectrically connected.

In some embodiments, the thermal conductivity of the first circuit board2 is better than that of the third circuit board 7. In specific, thethermal conductivity coefficient of the first circuit board 2 is higherthan that of the third circuit board 7, or during the unit time thefirst circuit board 2 can conduct more heat than the third circuit board7 (assuming other conditions are the same). Therefore, the heatgenerated during the operation of the light source 21 can be quicklyconducted to the lamp tube 1 through the first circuit board 2 anddissipated to the outside through the lamp tube 1. In addition, the heatgenerated by the light source 21 is not easily conducted to the thirdcircuit board 7, thereby impacting the power supply 5.

In some embodiments, the thermal conductivity of the third circuit board7 is better than that of the second circuit board 51. In specific, thethermal conductivity coefficient of the third circuit board 7 is higherthan that of the second circuit board 51, or during the unit time thethird circuit board 7 can conduct more heat than the second circuitboard 51 (assuming other conditions are the same). The electroniccomponent 52 of the power supply 5 includes a heating element, such as aresistor, a transformer, an inductor, an IC (Integrated Circuit), etc.In order to improve the heat dissipation of the power supply 5, at leastone of the heating elements of the electronic component 52 can thermallycontact the third circuit board 7 and the third circuit board 7 canthermally contact the lamp tube 1, so that a portion of the power supply5 can be thermally conducted to the lamp tube 1 through the thirdcircuit board 7 for heat dissipation. In some embodiments, the heatingelements of the electronic component 52 may also contact the thirdcircuit board 7 indirectly by dissipating heat in the form of heatradiation to the third circuit board 7.

In summary, the thermal conductivity coefficient of the first circuitboard 2, the third circuit board 7, and the second circuit board 51decreases in order.

In this embodiment, the hardness of the first circuit board 2 is greaterthan that of the third circuit board 7. Therefore, to the first circuitboard 2, the first circuit board 2 can better carry and support thelight source 21, and as to the third circuit board 7 the foldablefeature can make the first circuit board 2 and the second circuit board51 be connected through the third circuit board 7 with more adjustablespace and facilitating the connection. In this embodiment, the firstcircuit board 2 may be either one of a strip-shaped aluminum substrateand a glass cloth substrate (FR4).

In this embodiment, the hardness of the second circuit board 51 isgreater than that of the third circuit board 7. To the second circuitboard 51, the second circuit board 51 can better carry and support theelectronic components 52 of the power supply 5. When the power supply 5and the third circuit board 7 are stacked, the third circuit board 7 canbe bent and deformed to adapt to the power supply 5 to prevent thesetting of the third circuit board 7 from affecting the normalinstallation of the power supply 5.

In specific, in this embodiment, the first circuit board 2 is fastenedon the inner surface of the lamp tube 1 while the third circuit board 7is not fastened on the inner surface of the lamp tube 1. The thirdcircuit board 7 may be a soft circuit board or a flexible circuit board.There are two ends disposed on the second circuit board 51 in the axialdirection of the lamp tube 1 (the first end and the second end, wherethe first end is closer to the matching lamp cap 3) and one end iscloser to the matching lamp cap 3, the second circuit board 51 is closerto one end of the matching lamp cap 3 and connected to one end of thethird circuit board 7 while the other end of the third circuit board 7is connected to the first circuit board 2. During the installation andconnection process, the second circuit board 51 can be inserted into thelamp tube 1 first, and connect one end of the matching lamp cap 3 closerto the second circuit board 51 to one end of the third circuit board 7.The second circuit board 51 is closer to one end of the matching lampcap 3 connected to one end of the third circuit board 7. Becauseinsertion is completed in advance, there is no need to connect thesecond circuit board 51 to the first circuit board 2 as in the priorart, and then insert the second circuit board 51 into the lamp tube 1 asa whole, thereby lowering the difficulty of the production process andsolving the problem that the second circuit board 51 is difficult toinsert in the prior art.

In this embodiment, the second circuit board 51 and the third circuitboard 7 may be connected through connectors such as male and femaleplugs, pin headers, or the second circuit board 51 and the third circuitboard 7 may be directly soldered.

Please refer to FIG. 20 and FIG. 21, in this embodiment, the connectionbetween the third circuit board 7 and the first circuit board 2 may bedirectly soldered, or adopted a male and female plug, a pin, or the likefor connection. Preferably, the third circuit board 7 and the firstcircuit board 2 in this embodiment are connected by soldering.Specifically, there is a first pad 201 at one end of the first circuitboard 2, and there is a second pad 71 at one end of the third circuitboard 7 where the first pad 201 and the second pad 71 are directlysoldered (connected by soldering).

In this embodiment, the first pad 201 is spaced from the length end ofthe first circuit board 2 to form a connection section 202. One end ofthe third circuit board 7 is placed on the connection section 202 andthe second pad 71 corresponds to the first pad 201 in the lengthdirection of the lamp tube 1. The connecting section 202 is a part ofthe first circuit board 2, and its hardness is greater than that of thethird circuit board 7. Therefore, the third circuit board 7 can bettersupport and facilitate the connection. When the third circuit board 7 isplaced on the connection section, the end of the third circuit board 7rests on the first pad 201 (or maintain a minimum distance, such as thedistance between the end of the third circuit board 7 and the first pad201 in the length direction of the lamp tube 1 is less than 0.5 mm). Atthis time, the first pad 201 and the second pad 71 may be in contactwith each other, or keeping smaller distance to further facilitateconnection. In this embodiment, the number of the first pad 201 and thesecond pad 71 are three sets each, and each of them corresponds to eachother. The quantity of the first pad 201 and the second pad 71 is notlimited to this embodiment, and the specific quantity depends on thecircuit design requirement.

In this embodiment, the first pad 201 is disposed on a side of the firstcircuit board 2 with the light source 21. The second pad 71 is disposedon a side of the third circuit board 7 relatively close to a side of theelectronic component 52.

When the second circuit board 51 and the third circuit board 7 areactually connected, the ends of the second circuit board 51 and thethird circuit board 7 are partially exposed outside of the lamp tube 1,and the ends of the second circuit board 51 and the third circuit board7 are connected outside the lamp tube 1. After the second circuit board51 and the third circuit board 7 are connected, they are pushed into thelamp tube 1. Under this premise, the third circuit board 7 is allocateda soft circuit board, so that when the second circuit board 51 and thethird circuit board 7 are inserted into the lamp tube 1, the thirdcircuit board 7 can be bent to complete the above-mentioned actions. Inthis embodiment, when the third circuit board 7 is in the flat-straightstate, the end portion of the third circuit board 7 at least partiallyextends beyond the lamp tube 1 in the axial direction of the lamp tube1.

In this embodiment, the second circuit board 51 and the third circuitboard 7 are separated by an electronic component 52, thereby reducingthe risk of ignition caused by the second circuit board 51 contactingthe third circuit board 7. The above-mentioned electronic component 52includes relatively large-volume components such as capacitors,transformers, and inductors to ensure a sufficient distance between thesecond circuit board 51 and the third circuit board 7.

In this embodiment, in terms of the width direction of the lamp tube 1,the second circuit board 51 and the third circuit board 7 are disposedat opposite sides of the lamp tube 1. In other words, a central axis isin the lamp tube, and the central axis passes through the lamp tube 1parallel to the plane of the second circuit board 51. At this time, thesecond circuit board 51 and the third circuit board 7 are respectivelydisposed on both sides of the plane. In this way, it is ensured that thefirst circuit board 2 and the second circuit board 51 have a certaininterval, thereby lowering the risk of fire because the first circuitboard 2 contacts the second circuit board 51.

In this embodiment, the thickness of the third circuit board 7 issmaller than the thickness of the second circuit board 51. When thepower supply 5 and the third circuit board 7 are stacked and the innerdiameter of the lamp tube 1 is the same, controlling the thickness ofthe third circuit board 7 can provide more space for the power supply 5to facilitate the power supply 5 to more easily select and arrange theelectronic components 52. In this embodiment, the thickness of the thirdcircuit board 7 is also smaller than the thickness of the first circuitboard 2.

Please refer to FIG. 22, in some embodiments, an LED tube lamp which thebasic structure is the same as the LED tube lamp of the previousembodiments, except that the first circuit board 2 is fastened on theinner surface of the lamp tube 1 while the third circuit board 7 is notfastened on the inner surface of the lamp tube 1. The third circuitboard 7 may be a soft circuit board or a flexible circuit board.

There are a first end and a second end on the second circuit board 51 inthe axial direction of the lamp tube 1, wherein the first end is closerto the matched lamp cap 3, and the second end of the second circuitboard 51 is connected to the third circuit board 7 while the other endof the third circuit board 7 is connected to the first circuit board 2.During the assembly and connection process, the second circuit board 51is completely exposed outside of the lamp tube 1, so that the second endthereof is exposed outside of the lamp tube 1, and the end of the thirdcircuit board 7 is exposed outside of the lamp tube 1, therebyfacilitating the second end of the second circuit board 51 connected tothe end of the third circuit board 7. After the connection is completed,the second circuit board 51 is pushed into the lamp tube 1. In thisembodiment the second circuit board 51 and the third circuit board 7 maybe connected through male and female plugs and pin header connectors, orthe second circuit board 51 and the third circuit board 7 may bedirectly soldered together.

Please refer to FIG. 23 to FIG. 29, in some embodiments, a connectionmethod between a power supply 5 and a hollow conductive pin 4 isdisclosed. The LED tube lamp in these embodiments includes a connectingwire 8, and the hollow conductive pin 4 is fastened on the lamp cap 3.One end of the connecting wire 8 is electrically connected to the hollowconductive pin 4 (the connecting wire 8 and the hollow conductive pin 4are electrically connected through contact), the other end of theconnecting wire 8 is connected to the second circuit board 51, and theconnecting wire 8 is configured to reach a certain degree of thetemperature when fusing occurs (for instance when the temperaturereaches 300° C.), that is, when the LED tube lamp operates and arcingoccurs, and reaching a certain temperature, the connecting wire 8 willbe blown to protect from the over-heated problem, in order to preventthe LED tube lamp from further danger due to inflammation. In order toachieve the above purpose, the connecting wire 8 may include a fusibleportion 81, and the fusible portion 81 may use a low melting pointconductive material to reach the connecting wire 8 at a certaintemperature (when the melting point of the fusible portion 81 isreached), The purpose of fusing is to disconnect the connecting wire 8.The fusible portion 81 may be a low-melting alloy (such as a meltingpoint lower than 300° C.) such as bismuth, cadmium, tin, lead, thallium,or indium, or the above-mentioned elements or a combination thereof as amain component. In addition, the low-melting-point materials of theabove elements or combinations thereof can be configured to havedifferent melting points, so the materials can be specifically selectedaccording to actual needs.

In some embodiments, the melting point of the fusible portion 81 is lessthan or equal to that of any electronic component on the second circuitboard 51, the second circuit board 51 itself or the electronic componentused to connect the second circuit board 51 with the second circuitboard 51. From another perspective, the melting point of the fusibleportion 81 is less than or equal to the melting point of any conductivesubstance on the second circuit board 51. In order to ensure when thetemperature is too high, the fusible portion 81 is first disconnected toavoid a condition in which the conductive material on the second circuitboard 51 is melted and a short circuit or even a fire occurs on thesecond circuit board 51.

As shown in FIG. 23, in this embodiment, the entire connecting wire 8 iscomposed of a fusible portion 81, that is, the entire connecting wire 8is made of a low-melting conductive material. In some embodiments, theconnecting wire 8 may only include a part of the fusible portion 81(described in FIG. 13). When the cost of the material of the fusedportion 81 is high (compared to the connecting wire 8), this method canreduce the cost. In this embodiment the melting point of the fusibleportion 81 is lower than the melting point of the remaining portions ofthe connecting wire 8.

In some embodiments, if the second circuit board 51 and the firstcircuit board 2 are connected through a connecting wire 8, theconnecting wire 8 is used to connect the second circuit board 51 and thefirst circuit board 2 may also adopt the above technical solution, thatis, the connecting wire 8 includes fusible portion 81. In order toachieve the result of arc protection (over-heated protection).

As shown in FIG. 23, in order to prevent the fusible portion 81 of thetwo connecting wires 8 from being short-circuited due to contact afterthe fusible portion 81 is melted. The following installations can bemade: the distance between the two hollow conductive pins 4 is L1, andthe length L2 of the fusible portion 81 of the connecting wire 8 is setto be shorter than the distance of the two hollow conductive pins 4 isL1. Therefore, when the two hollow conductive pins 4 are set up anddown, even if the fusible portion 81 is melted and one end is separatedfrom the second circuit board 51, when the fusible portion 81 is bentdue to gravity, it cannot contact the lower connecting wire 8 due to itslength. As shown in FIG. 27, a schematic diagram shows the upper fusibleportion 81 is bent downward. As shown in FIG. 29, if the entireconnecting wire 8 is composed of a fusible portion 81, the length L2 ofthe fusible portion 81 is calculated as a portion of the connecting wire8 exposed outside the hollow conductive pin 4.

In some extreme cases, the fusible portion 81 is melted and one end isseparated from the second circuit board 51. The fusible portion 81 isbent due to gravity, and the fusible portions 81 of the two connectingwires 8 are relatively bent at the same time. The length L2 of thefusible portion 81 is set to be less than half of the distance L1 of thetwo hollow conductive pins 4, that is, even if the two fusible portions81 are relatively bent, a short circuit does not occur. As shown in FIG.28, a schematic diagram shows the two fusible portions 81 are relativelybent.

As shown in FIG. 26, the connection of the connecting wire 8 and thesecond circuit board 51 is shown. An adsorption portion 514 is disposedon the second circuit board 51, and one end of the fusible portion 81 ofthe connecting wire 8 is electrically connected to the adsorptionportion 514. The adsorption portion 514 is a conductive material. Afterthe fusible part 81 is connected to the end of the adsorption part 514and is melted, the adsorption part 514 can adsorb and gather thematerial of the melted fusible part 81 to prevent the fusible part 81from flowing to other places and cause a short circuit, and so on. Whenthe fusible portion 81 is made of tin or mainly tin, the adsorptionportion 514 is a metal material, particularly copper, and has thefunction of adsorbing and gathering the fusible portion 81. The meltingpoint of the adsorption portion 514 is higher than the melting point ofthe fusible portion 81.

Please refer to FIG. 24, a schematic diagram of a circuit board of anLED tube lamp according to an embodiment is shown. The circuit board inthis embodiment includes at least two connecting portions 91 and the twoconnecting portions 91 are electrically connected (electricallyconnected). Specifically, the connecting portions 91 are connected toeach other through the connection unit 92. The connection unit 92includes a fusible portion 921. When an arc is drawn near the connectingportion 91 or the temperature is too high, the fusible portion 921causes the connecting portion 91 to melt. The electrical connection isthen broken. The fusible portion 921 may use a low-melting conductivematerial (melting point is lower than 300° C.) to achieve the purpose ofthe connection unit 92 to fuse at the fusible portion 921 at a certaintemperature, so that the connection unit 92 is disconnected and the twoconnecting portions 91 are disconnected. An open circuit is formed toprotect it (arc protection, over-heated protection). Compared with theprior art, two wires are used to connect the two connecting portions orcopper wires are used to connect the two connecting portions, andtherefore improves safety.

The fusible portion 921 may be a low-melting alloy (having a meltingpoint below 300° C.) such as bismuth, cadmium, tin, lead, thallium, orindium, or the above elements or a combination thereof as a maincomponent. And the low melting point materials of the above elements orcombinations thereof have different melting points, so they can beselected according to actual needs.

In this embodiment, the connection unit 92 may be composed of only thefusible portion 921. In some embodiments, the connection unit 92includes only a part of the fusible portion 921. When the cost of thematerial the fusible portion 921 is high, this method can reduce thecost.

In this embodiment, the circuit board may be the second circuit board 51or the first circuit board 2 described above, or may be anothercomponent having a connecting portion.

As shown in FIG. 25, in this embodiment, an absorption unit 93 may befurther provided between the two connecting portions 91. The fusibleportion 921 at least partially contacts the absorption unit 93. Afterthe fusible portion 921 is melted, the absorption unit 93 adsorbs thefusible portion 921, so the materials of the melting portion 921 aremelted to ensure that after the melting portion 921 is melted, themelting portion 921 is broken due to the adsorption effect of theabsorption unit 93. For example, when the fusible portion 921 is made oftin or mainly tin, the absorption unit 93 is made of a material that caneasily absorb tin, such as a metal material, especially copper.Alternatively, the absorbing unit 93 is made of the same material as theconnecting portion 91 to achieve the function of adsorbing the materialafter the melting portion 921 is melted.

In this embodiment, the melting point of the fusible portion 921 is lessthan or equal to the melting point of any electronic component on thecircuit board, the circuit board itself, or the electronic componentused to connect the circuit board with the circuit board. From anotherperspective, the melting point of the fusible portion 921 is less thanor equal to the melting point of any conductive substance on the circuitboard. In order to ensure that the temperature is too high, the fusibleportion 921 is first broken off to avoid a situation where a conductivematerial on the circuit board is melted and a short circuit or even afire occurs on the circuit board.

Preferably, in this embodiment, the melting points of the materials ofthe connecting portion 91, the absorption unit 93, and the circuit boardcorresponding to the fusible portion 921 is higher than the fusibleportion 921, so as to ensure that the connecting portion 91, theabsorption unit 93, and the circuit board will not melt before thefusible portion 921 melts.

While the preferred embodiment of the invention has been set forth forthe purpose of disclosure, modifications of the disclosed embodiment ofthe invention as well as other embodiments thereof may occur to thoseskilled in the art. Accordingly, the appended claims are intended tocover all embodiments which do not depart from the spirit and scope ofthe invention. The disclosure of all articles and references, includingpatent applications and publications, is hereby incorporated byreference for all purposes. The omission of any aspect of the subjectmatter disclosed herein in the preceding claims is not intended toabandon the subject matter, nor should the inventor be considered tohave considered the subject matter as part of the disclosed subjectmatter.

What is claimed is:
 1. An LED tube lamp, comprising: a lamp tube; afirst circuit board, disposed in the lamp tube, having a plurality oflight sources mounted thereon; two lamp caps disposed at respective endsof the lamp tube; a power supply substantially disposed in one or bothof the two lamp caps, the power supply having a second circuit board;and a connection structure having a third circuit board, the thirdcircuit board for connecting the first circuit board to the secondcircuit board thereby connecting the light sources to the power supply.2. The LED tube lamp of claim 1, wherein the thermal conductivity of thefirst circuit board is higher than that of the third circuit board. 3.The LED tube lamp of claim 1, wherein the thermal conductivity of thethird circuit board is higher than that of the second circuit board. 4.The LED tube lamp of claim 3, wherein the power supply includes anelectronic component, the electronic component of the power supplyincludes one or more heating elements, at least one of the heatingelements of the electronic component thermally contacts to the thirdcircuit board.
 5. The LED tube lamp of claim 3, wherein the power supplyincludes an electronic component, the electronic component of the powersupply includes a heating element, the heating element for dissipatingheat in the form of heat radiation to the third circuit board.
 6. TheLED tube lamp of claim 1, wherein the hardness of the first circuitboard is greater than that of the third circuit board.
 7. The LED tubelamp of claim 1, wherein the hardness of the second circuit board isgreater than that of the third circuit board, the power supply and thethird circuit board are stacked, and the third circuit board is bent anddeformed to adapt to the power supply.
 8. The LED tube lamp of claim 1,wherein the first circuit board is fastened on the inner surface of thelamp tube while the third circuit board is not fastened on the innersurface of the lamp tube, and the third circuit board is a soft circuitboard or a flexible circuit board.
 9. The LED tube lamp of claim 1,wherein the second circuit board has a first end and a second end in aaxial direction of the lamp tube, and the first end of the secondcircuit board is closer to the matching lamp cap, the first end of thesecond circuit board is connected to one end of the third circuit boardwhile the other end of the third circuit board is connected to the firstcircuit board.
 10. The LED tube lamp of claim 9, wherein the secondcircuit board is directly soldered to the third circuit board.
 11. TheLED tube lamp of claim 10, wherein the first circuit board has a firstpad, and the third circuit board has a second pad, the first circuitboard and the third circuit board are directly soldered through thefirst pad and the second pad.
 12. The LED tube lamp of claim 11, whereinthe first pad of the first circuit board is spaced from the end of thefirst circuit board in a longitudinal direction to form a connectionsection, one end of the third circuit board is placed on the connectionsection and the second pad of the third circuit board corresponds to thefirst pad of the first circuit board in the length direction of the lamptube.
 13. The LED tube lamp of claim 12, wherein the connection sectionis a part of the first circuit board, and the hardness of the connectionsection is higher than that of the third circuit board.
 14. The LED tubelamp of claim 11, wherein the power supply includes an electroniccomponent, the first pad of the first circuit board is disposed on aside of the first circuit board with the light sources, and the secondpad of the third circuit board is disposed on a side of the thirdcircuit board relatively close to a side of the electronic component.15. The LED tube lamp of claim 1, wherein the second circuit board andthe third circuit board are separated by the electronic component. 16.The LED tube lamp of claim 15, wherein the electronic component includesone of a capacitor, transformer or inductor.
 17. The LED tube lamp ofclaim 1, wherein the second circuit board and the third circuit boardare disposed at opposite sides in the width direction of the lamp tube.18. The LED tube lamp of claim 1, wherein the thickness of the thirdcircuit board is smaller than that of the second circuit board.
 19. TheLED tube lamp of claim 1, wherein a hollow conductive pin is arranged onthe lamp cap, the LED tube lamp includes a connecting wire, and thehollow conductive pin is fastened on the lamp cap, one end of theconnecting wire is electrically connected to the hollow conductive pin,the other end of the connecting wire is connected to the second circuitboard, the connecting wire includes a fusible portion and the fusibleportion is a low-melting alloy.
 20. The LED tube lamp of claim 19,wherein the melting point of the fusible portion is less than or equalto the melting point of any conductive substance on the second circuitboard.